Barrier layer for photocatalytically active composite material

In a composite material having a construction that on the surface of a substrate is formed a primer layer having an appropriate function, and a photocatalyst layer is laminated on the primer layer, decreasing of the durability of the film due to the existence of the primer layer is prevented. Primer layer 14, photocatalyst layer 16, and hydrophilic layer 18 are laminated on one surface of transparent glass substrate 12 in this order. Primer layer 18, which makes up for suppressing sodium dispersion, is composed of a mixture or double oxide comprising an inorganic oxide such as SiOand AlO, and lanthanoide oxide such as La, Ce, and Pr, or of TaOor ZrO. Photocatalyst layer 16 comprises, e.g., the photocatalyst, TiO. Hydrophilic layer 18 comprises, e.g., porous SiO.